Inclusion Criteria:

• * Men age 18 or older
• * Patient has diagnosis of pathologically confirmed prostate cancer, treated with radical prostatectomy. Any type of radical prostatectomy will be permitted, including retropubic, perineal, laparoscopic, or robotically assisted
• * Patient has pathologic T2-T3M0 stage. Patients can have 5 or less metastatic pelvic lymph nodes confirmed by pathology
• * For patients radiated in the post-operative salvage setting: pathology can demonstrate any of the following features but not required, positive margin, extracapsular extension, or seminal vesicle involvement with detectable prostate-specific antigen (PSA) of \>= 0.1. PSA \>= 0.1 after radical prostatectomy: most recent PSA value within 12 months of registration and prior to initiating any androgen deprivation therapy (ADT)
• * Patient diagnosed with Gleason score of 6-10
• * Eastern Cooperative Oncology Group (ECOG) performance 0-2
• * Patients may receive 6 months and up to 24 months of androgen deprivation therapy. Patients may have received androgen deprivation therapy up to 12 months prior to postoperative radiotherapy
• * If the patient has a prior history of any cancer other than prostate cancer, he must have completed treatment within 1 year of study registration and the patient must have no evidence of disease of this prior non-prostate cancer

Exclusion Criteria:

• * Prior radiation therapy to prostate/seminal vesicle fossa or postoperative region
• * Neoadjuvant chemotherapy before or after prostatectomy
• * History of lupus, scleroderma, or calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia (CREST) syndrome
• * History of severe active co-morbidity or uncontrolled diabetes
• * Unstable angina and/or congestive heart failure requiring hospitalization within the last 6 months
• * Transmural myocardial infarction within the last 6 months
• * Severe hepatic disease, defined as a diagnosis of Child-Pugh class B or C hepatic disease
• * End-stage renal disease (i.e., on dialysis or dialysis has been recommended)